1. Field of the Invention
The present invention relates to a plug blade structure with a shallow recess and a reinforced guide slot for forming an insulating layer, thereby preventing generation of a fault on an outer surface of the insulating layer.
2. Description of the Related Art
A plug is a necessary element to all industries and other fields. The plug is engaged with a socket to supply electricity to an electric appliance or other electric equipments.
Most advanced countries require each blade of the plug to be partially wrapped by an insulating layer at an exposed section thereof, thereby avoiding electric shocks to the user. The insulating layer is generally made of plastic material and wraps a portion of the exposed section of the blade by means of injection molding. However, the insulating layer is apt to be disengaged from the smooth metal surface of the blade as a result of poor bonding force therebetween. Thus, the insulating layer would slide easily, and sometimes may even fall. The blade is then exposed again and thus could cause an electric shock.
It has been proposed to provide a plug blade including an enclosed section and an exposed section. The exposed section includes a wider front section and a narrower rear section having a transverse through-hole. Plastic material is filled to a face of the narrower rear section and flows through the transverse through-hole to the other face of the narrower rear section. An insulating layer is formed on the narrower rear section after hardening of the plastic material. The bonding force between the insulating layer and the narrower rear section is improved, and the time for filling the plastic material is reduced. Soviet Union Pat. No. SU 1388,969-A discloses a similar structure. However, a fault (generally a shallow recess) is formed on a surface of the insulating layer after hardening of the plastic material. The appearance of the plug is thus adversely affected.
An object of the present invention is to provide a plug blade structure to provide an aesthetic appearance in the insulating layer after formation.
A plug blade structure in accordance with the present invention comprises an enclosed section and an exposed section. The exposed section includes a wider front section and a narrower rear section. The enclosed section includes a shallow recess in a front end thereof for filling molten plastic material into the narrower rear section. A transverse through-hole extends from a face of the narrower rear section to the other face of the narrower rear section. A reinforcing guide slot is defined in the narrower rear section and communicated with the transverse through-hole. The transverse through-hole and the reinforcing guide slot guide the molten plastic material from a face of the narrower rear section to the other face of the narrower rear section.
Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.